1. Field of the Invention
This invention relates to an oil fence having a limited flexibility, and more particularly to an oil fence having a limited flexibility which is to be pulled by a ship for recovering pollutants, e.g., split oil, from water surface.
2. Description of the Prior Art
To recover spilt oil or other pollutants from water surface, an oil fence having a long belt member which is flexible in three-dimensional directions has been used. The three-dimensionally flexible belt member, however, has a shortcoming in that it may turn from a vertical posture to a horizontal posture so that the pollutants might pass across the horizontal belt member. Thus, the flexible belt member fails to fulfill the desired object of collecting the pollutants.
Furthermore, the three-dimensionally flexible belt member allows the pollutant-carrying water to flow in a direction which is substantially perpendicular to the cruising direction of the ship pulling the belt member. The line of the long belt member is, of course, arcuately curved on the water surface when such perpendicular flow of the pollutant-carrying water is allowed. It has been found that when the flow rate of the pollutant-carrying water, relative to the longitudinal direction of the belt member, exceeds a certain value, the pollutants tend to by-pass the belt member by flowing underneath it together with the water. Such by-pass of the pollutants across the belt member is apparently detrimental to effective collection of the pollutants.
Therefore, an object of the present invention is to overcome the aforesaid difficulties of the conventional oil fence, by providing an improved oil fence which has a limited flexibility.